Under the 3GPP standards, a NodeB is the base station via which mobile devices connect to the core network. Recently the 3GPP standards body has adopted an official architecture and started work on a new standard for home base stations (HNB). One or more HNBs will provide radio coverage within the home and will connect to the core network via one or more suitable public networks (for example via an ADSL link to the Internet) via an HNB gateway (HNB-GW) which will aggregate traffic from the one or more HNBs.
When User Equipment (UE) attempts to make an RRC Connection in the macro UTRAN network, a Radio Network Controller (RNC) will allocate the U-RNTI to the UE to identify the UE to the network. However, with HNBs, the RNC functionality is divided between the HNB and the HNB-GW and at present it is not clear which entity will be responsible for allocating the U-RNTI.
A separate but related problem relates to mobility of UEs when in the CELL FACH connected state. Such mobility is not supported in Release 8 (Rel'8), but is currently under discussion in Release 9 (Rel'9). In the CELL FACH state, the UE makes the decision to handover to another (target) HNB and sends the target HNB an RRC CELL UPDATE message indicating that it wants to handover to the target HNB. The target HNB or the HNB-GW must then be able to identify the source HNB with which the UE is currently registered, so that it can obtain various Information Elements (IEs) from the source HNB that will allow the target HNB to be able to communicate with the UE.